Heat-shock treatment reduces in situ temperature in yeast at sub-lethal high temperature

Cells from the yeast Schizosaccharomyces pombe IFO-0342, once heat shocked and then treated with ultra-centrifugation showed a significant increase in tolerance compared to non heat-shocked control cells as estimated by colony forming unit (CFU). Fluorescence microscopical observation of these treated cells when stained with DAPI revealed that in non heat-shocked cells the chromatin regions were dislocated to one end due to the acceleration force of gravity. However, prior heat-shocked cells or 2.0 M glycerol suspended cells showed normal localization. From these results, it has been postulated that the interior part of the heat-shocked cells becomes viscous, and that in situ the temperature of the cell interior part might be reduced under semi-lethal high temperature.